Fecundity

Fecundity Definition

Fecundity is a measure of the number of offspring produced by an organism over time. It is also called the reproductive rate of an organism. Fecundity is measured by the number of offspring that are created successfully. In sexually reproducing organisms, two gametes must meet and the process of fertilization must occur. This embryo must then be developed, and birthed into the world, either directly from the zygote, or from a seed, an egg, or directly from the mother. Fecundity is a measure of the number ofviable offspring, or offspring that have the potential to continue on reproducing. Fertility, on the other hand, is simply the ability to sexually reproduce successfully.

A population exhibits more fecundity when each organisms produces more offspring successfully, and the population grows. Fertility is simply a description of whether or not individual animals are able to reproduce. An organism can produce many gametes ready for fertilization, but may never get the chance to reproduce. This organism would be fertile, but would show no fecundity. Fecundity can be measured in individual organisms, or in entire populations. The study of human demographics uses the measure of fecundity to help determine the rate of change a population is experiencing. Ecologists also use measures of fecundity to study reproductive rates in animal populations.

Related Biology Terms

Sterility – The opposite of both fertility and fecundity, or the complete inability to reproduce.

Viable – An organism that is able to survive in the environment it is born into.

Quiz

1. A female giraffe has the ability to produce eggs in her ovaries, and seems healthy enough to carry a baby to term. However, she is kept in a zoo with no males, and never gets the chance to reproduce. Which of the following statements about the giraffe is true?A. She is fertile, but displayed no fecundity over her life.B. Fecundity and fertility both abound from this giraffe.C. This giraffe shows neither fecundity for fertility.

Answer to Question #1

A is correct. This giraffe is fertile, because she has the ability to reproduce. The problem comes in finding a mate. In this way, her fecundity is limited. This is a problem for many animals, and almost all animals have special methods by which their mating takes place to ensure the fecundity of individuals that are fertile. Many fish, birds, mammals, and even many invertebrates display intimate mating rituals between members of the opposite sex. This leads to an increased fecundity among fertile individuals. An infertile individual will never show fecundity, as they lack the ability to reproduce.

2. A frog lays 200 eggs in a small batch in a pond. The eggs hatch, the tadpoles emerge, and many are eaten on their way to adulthood. By the time this generation is ready to reproduce, there are only 20 frogs left. This cycle continues yearly. A deer reproduces one baby per year, ever year, for 30 years. Over time, only 5 of the babies are eaten by predators, leaving 25 surviving deer, ready to reproduce. Which of these organisms shows the greatest fecundity?A. The DeerB. The FrogsC. Neither, they are the same.

Answer to Question #2

B is correct. The frogs have by far the greater fecundity. Each reproductive adult is capable of producing 200 viable offspring. Many of these offspring do not reach adulthood. However, that is a measure of offspring survival, not fecundity. A deer can only produce 1 to 2 offspring at a time, which is far fewer viable offspring than each frog. However, the deer get eaten at a much slower rate, and the evolution strategy they employ resolves around a higher level of parental care, much like humans.